1. Field of the Invention
The invention relates to interfaces for example between optical readers and related components and to finger mounted optical readers, for example ring scanners.
2. Description of the Related Art
Various optical readers and optical scanning systems have been developed heretofore for reading indicia such as bar code symbols appearing on the label or on the surface of an article. The symbol itself is a coded pattern of indicia comprised of, for example, a series of bars of various widths spaced apart from one another to bound spaces of various widths, the bars and spaces having different light reflecting characteristics. The readers in scanning systems electro-optically transform the graphic indicia into electrical signals, which are decoded into alphanumeric characters that are intended to be descriptive of the article or some characteristic thereof. Such characteristics are typically represented in digital form and utilized as an input to a data processing system for applications in point-of-sale processing, inventory control and the like. Scanning systems of this general type have been disclosed, for example, in U.S. Pat. Nos. 4,251,798; 4,369,361; 4,387,297; and 4,409,470; 4,760,248; 4,896,026, all of which have been assigned to the present applicant. As disclosed in the above patents, one embodiment of such scanning systems includes, inter alia, a hand held, portable laser scanning device supported by a user, which is configured to allow the user to aim the scanning head of the device, and more particularly, a light beam, at a targeted symbol to be read.
Such prior art hand held devices generally incorporate a light-receiving module which receives the light that has been reflected from the bar code symbol and determines, from the reflected pattern, the sequences of bars and spaces within the symbol. The unit may also incorporate decoding circuitry to decode the received information and to recover the underlying data (for example the alphanumeric data) which the bar code symbol represents.
However in some cases it is undesirable to have to grip the scanner in one hand as this reduces the user's maneuverability and capability to use both hands to lift objects and so forth. At the same time it is not desired to lose a particular advantage of a handheld scanner that it can be pointed in a desired direction.
Various solutions have been proposed to overcome these problems, in particular providing a finger mounted scanner. Whilst existing systems have met with success, it is nonetheless desirable to improve systems yet further, in particular in terms of their adaptability, flexibility and processing and scanning power. One known scanner is described in U.S. Pat. No. 5,578,810, commonly assigned herewith and incorporated herein by reference.
U.S. Pat. No. 3,978,318 relates to a scanner mounted on an inverted T extension, the stem of the extension being received between two of the user's fingers when the base rests on the user's palm. The system therefore requires that the user grips the extension tightly at all times which is inconvenient and uncomfortable.
In another aspect it is desired to improve the performance of interfaces between scanners and associated components. In particular, at present, many scanners cannot discern between bar code symbols and accidental surface patterns resembling bar code symbols, for example wood grain, dirt or texture on the base of a console holding the scanner. This is a particular problem where the scanner is not manually triggered but is permanently operative.
It is a general object of the present invention at least to alleviate some of the problems associated with the prior art. It is a further object to provide a ring scanner having improved adaptability.
It is a further object of the present invention to provide a scanner having reduced probability of accidentally reading surface patterns resembling bar code symbols.